Air conditioning apparatus



y 9, 1961 G. w. WOOD AIR CONDITIONING APPARATUS Filed Jan. 15, 1959 INVENTOR.

GEORGE W. WOOD BY ATTO NEY :Pe e i.

' Pa., a corporation of Pennsylvania Filed Jan. 13, 19s9, ser.-No'. 786,594

scni s. (or. 251-131 This invention relates to air conditioning apparatus and more particularly to airflow systems in compact, unit type or self-contained air conditioners. It deals more particularly with the noise and efiiciency involved in directing air against the inlet face of afinned tube heat transfer unit 'which serves to change the temperature ofthe air delivered to the enclosure. 7

f The demand for greater. compactness in air conditioning units of 'the type adapted'to be mounted in a" window or o'theropening of a' building for cooling an enclosure has heces'sitated unit desig s .Which employ other thanideal 2 V made to the accompanying drawing,-forming a part hereof and in which: t V v Fig. l is a plan view of an air conditioning unit which embodies the invention and from which the top has been removed to show the interior of the unit; Fig. 2 is a vertical sectional view through theroom-air section of the unit, taken along line II II in, Fig. 1 and having portions broken'away to clarifythe'illustration; and, J. v j Fig. 3 is an enlarged fragmentary illustration of a portion of the evaporator of the air conditioner of Fig. l.-

,"Ihe'unit comprises 'a casing 11 having a partition 'l2 therein dividing the easing into a woman section 13 and an outdoor air section 14, The outdoora'ir section 14 houses a motor compressor unit 15 which supplies compressedrefrigerant to a condensing unit 16 which, in turn,

air flow systems. Particularly with respect to the room air 1 sectionof such units, crowding togetherthe components of the units, coupled with reduction in the size of air flow passages'has resulted inhighnoise' levels and inefiicient utilizationof heat exchanger surfaces. -The noise and efliciency problems-are particularly troublesome "when the location of'the room air blower"is si lch that'a'ir is directed obliquely. toward the face of the heat exchanger which functions, during cooling operation; as a cooling unit or evaporator, rather than at right angles to the f s Qfiith ,.h at.eX. a er-. M s t r condit o s,emrzbxfin edt be y a s and it b e Qbse edT at eirdi eetedwee e s t edges of the closely s a ed s e ueestu bu enee n the a rfie with es i noise.- Direc ting air obliquely towardthe face ofthe an ient-else result a ney i ib of the a ew: hreush-t ev ora r a d, notell r sef h evaporator are effectively utilized.

It is the principal object of this invention to elfect a reduction in the noise emanating from air flow systems having the deficiencies noted above and to increase the efliciency of heat transfer between the evaporator or heat transfer unit and the air flowing therethrough.

In accordance with this invention, the face of the evaporator or heat transfer unit at which air is directed is covered by a perforated sheet which preferably possesses a surface that is smooth, except for the perforations. Air directed against the face of an evaporator, for example, first encounters and flows over this perforated sheet which, because of the small size of the openings therein, offers less resistance to air flow across its surface and causes less noise to be generated than if the air impinged directly on the bare fins of the evaporator. The perforated sheet also introduces a limited overall restriction to air flow into the evaporator and uniform air pressure is built up across the face of the sheet, which causes air to flow uniformly through all areas of the evaporator. It has been found that this restriction, though effecting a reduction in the total quantity of air passing through the evaporator, actually results in greater overall cooling capacity because of the more etficient utilization of the evaporator surfaces. A

The several features, objects and advantages of this invention can be better understood from the following delivers liquid refrigerantto a cooling unit or evaporator 17 disposed within the indoor air section 13. Refrigerant is vaporized in the evaporator 17 to absorb heatfrom room air which is circulated over the evaporator by a motor-driven blower wheel '18. 'The evaporator '17 is formed of several serpentine passes of'refrigeranttubing 19 which have a plurality of closely spaced, thin metal fins lt) disposed transversely of the tubes in good heat transfer relation therewith. It is to be understood that so far: as :the'present invention is concerned the evaporator 17 is to be regarded as a heat transfer unit for changing the temperature of the air delivered to the room, the reference to an evaporator being given by way of example as apart of the illustrated embodiment; Room air enters the air conditioner through one face ofthecasingll beneath the evaporator 17 and enters a scroll shaped, blower casing 21 through an inlet opening 22 provided therein. The blower Wheel 18 rotates about a horizontal axis aligned with the center 'of opening-22, picks up'air flowing through the opening and propels it through the casing 21 and upwardly onto the evaporator 17 at the inlet thereof. As can best be seen in Fig. 1, the 'air conditioning unit embodying this invention is unusually compact, in that the several components thereof have been ,placed *as' closely together as possible, leaving but minimum space for air flow through the unit. For example, the blower wheel 18 is located as close to the evaporator 17 as possible. The wheel 18 is spaced slightly below the lower edge of the evaporator 17 (see Fig. 2) and is disposed in closely spaced relation to the plane of the inner, or inlet, face of the evaporator, indicated at 23. The disposition of the blower wheel 18 and its scroll casing 21 is such that air is discharged across the inner face 23 of the evaporator 17; Le, the general direction of air movement is more nearly at right angles to rather than parallel to the planes of the fins of the evaporator. The partition 12 is angled toward the inner face of the evaporator 17 at the end thereof opposite the blower wheel 18, as shown in Fig. *1, to direct air into the evaporator 17.

The inner face of the evaporator 17 is equipped with means for reducing noise that would otherwise result from -air impinging against the inlet edges of the evaporator fins 20. This means takes the form of a smooth surface, perforated sheet 24 which covers the inner face 23 of the evaporator. The sheet 24 is preferably'made of metal or plastic and is provided throughout its entire extent with a multiplicity of apertures or openings 25. Some of the openings have been omitted from the drawing to simplify the illustration. The sheet 24 is held against the inlet face of the evaporator 17 by suitable fastening means, such as nails 26 driven through openings in the sheet and wedged between fins 20 of the evaporator.

In operation, air issuing from the blower casing 21,

encounters the perforated sheet 24 and is prevented from striking the fins 20 of the evaporator 17. Sheet 24 presents a relatively smooth surface to the air flow so that the air moving thereover does not generate noise. The small openings 25 in the sheet 24 offer some resistance to air flow and pressure is built up between the sheet and the partition 12, causing air to flow evenly through the sheet and through all areas or regions of the evaporator 17. For atypical room cooling unit, the sheet 24 preferably has openings 25 therein whose diameters are of the order of .080 inch to-..0 9 inch, and the openings are spaced so as to provide at least 36% open area across the sheet. Forexarnple, a .032inchthick metal sheet, having .088 inch; diameter holes on l 25 inch staggered equilateral centers (40% open area) has been shown to be particularly elfective when used with evaporators having .007 inch thick fins spaced .076 inch apart (l4 fins per inch). It has'been shown by tests that, while the quantity of air flowing through the evaporator 17 is reduced somewhat by the introduction of the perforated sheet 24 into the air flow path, an actual increase in the cooling capacity'of the unit results from more efficient utilization of the evaporator surfaces in cooling air. Thus, the use of the perforated sheet 24 in the above described manner not onlyreffectively reduces noise that would otherwise emanate from the room air system of the unit but, in addition, improves the operating efiiciency of the unit.

While the invention has been shown in but one form, itwill be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof. What is-claim ed is: 1 1. In a compact, unit type air conditioner, a finned tube heat transfer unit having a substantially flat inlet face, the fins of said unit being disposed in spaced, substantially vertical planes arranged at right angles to said inlet face, a blower wheel, said blower wheel being located in closely spaced relation to the plane of said inlet face, a scroll casing for said blower wheel directing air from said wheel across the inlet face of said unit in a direction more nearly at right angles to than parallel to the planes of said fins, and means for reducing turbulence of air flowing across the inlet face of said unit and for distributing air through said unit, said means comprising a smooth face, perforated sheet disposed across said inlet face of said unit in contact therewith.

2. In a compact, unit type air conditioner, a finned tube heat transfer unit having a substantially flat inlet face, the fins of said unit being disposed in spaced, substantially vertical planes arranged at right angles to said inlet face, a blower wheel, said blower wheel being located in closely spaced relation to the plane of said inlet face, a scroll casing for said blower wheel directing air from said wheel across the inlet face of; said unit in a direction more nearly at right angles to than parallel to the planes of said fins, and means for reducing turbulence of air flowing across the inlet face of said unit and for distributing air through said unit, said means comprising a smooth face, perforated sheet disposed across said inlet face of said unit in contact therewith, said sheet being characterized by having a multiplicity of openings therein whose diameters are from .080 to .095 inch and are spaced so as to provide at least 36% open area through said sheet. Y 4

3. In a compact, unit type air conditionen a finned tube heat transfer unit having a substantially fiat and vertical inlet face, the fins of said unit being disposed in spaced, substantially vertical planes arranged at right angles to said inlet face, a blower wheel rotatable on a horizontal axis disposed at right angles to said inlet face, saidblower Wheel being located below the: loweredge of said unit in closely spaced relation to the plane of said inlet face and entirely outside -the horizontal extent of said unit, a scroll casing for said blower wheel directing air from said wheel across the inlet face of said unit in a direction more nearly at right angles to than parallel to the planes of said fins, and means for reducing turbulence of air flowing across the inlet face of said unit and for distributing air through saidunit, said means comprising a smooth face, perforated sheet disposed across said inletface of said unit in contact therewith.

References Cited in the file of this patent UNITED STATES PATENTS Smith ...L Nov. 19, 1957 

